This used to be one of my favourite experiments in my childhood. When the water in a glass is put into a spin by a DC motor from the top, the things lying at the bottom gets lifted to the top. The effect was particularly interesting because it resembles tornadoes. (Click to see Video) What ca...

For example the chemical energy of a kilogram of gasoline is 44-46 MJ/kg. It is only dependent on its chemical structure, which stays the same, whether the gas tank moves or stays still relative to the observer. But the kinetic energy of a car depends on the reference frame. In a reference frame...